1. Field of Invention
The invention relates to apparatus and methods for performing endoscopic, laparoscopic and percutaneous interventional surgery.
2. Description of Related Art
This invention is in the surgical therapies for the treatment of disease by blocking, or occluding, hollow anatomical structures within the body of a patient. The invention also relates to surgical therapies for the treatment of the surface of a hollow anatomical structure, wherein such treatments do not necessarily result in occlusion of the structure.
In many medical conditions such as arterio-venous vascular malformations and varicose veins, it is advantageous to block a blood vessel. In treating liver disease it is possible to induce liver regeneration by directing blood supply from one area to another, for example by blockage of portal blood to the right liver to induce hypertrophy of the left liver. Blocking blood flow can also be used in the field of oncology, specifically in the field of treating solid tumours. One method of treating tumours is to interrupt the blood supply to the tumour. In many tumours there are a small number of discrete vessels supplying blood to the tumour. Interrupting the blood supply to these vessels will cease the flow of nutrients to the tumour causing the tumour cells to die. Blood vessels that supply tumours can also be used to introduce an ablation device into the tumour.
Occlusion of non-blood vessels can also be desirable. Hollow anatomical structures include, for example, the fallopian tubes, small and large intestine, bronchi, bronchioles, biliary duct, urethra, ureters and vas deferens. In certain circumstances it may be desirable to occlude (fully or partially) a hollow anatomical structure. For example; ligation of the fallopian tubes is a well known means for achieving female sterilization. In other circumstances it may be desirable to treat the lumen-facing surface of the hollow structure so as to administer therapy to a lesion that is located on that surface.
Prior methods of inducing closure or occlusion of a hollow anatomical structure include injecting a sealing compound into the structure, or positioning a plug or obstructive stent into the structure. These have the disadvantage that these blocking structures may move over time. For instance, where a blood vessel that leads to a tumour has been occluded loss or displacement of the occluding structure can permit resumption of blood flow through the tumour supplying vessel. In some cases the structure may move to another vessel and cause an embolism.
Thermal ablation of hollow anatomical structures has been utilised in the percutaneous treatment of venous disorders such as varicose veins as well as in endoscopic tubal ligation for achieving female sterilization. Hollow anatomical structures, such as blood vessels, are treated in this way by local heating. This heating may be applied by exposing the tissue in the tube or vessel to locally applied electro-magnetic or ultrasound energy. The electro-magnetic energy may be at radio-frequencies, or micro-wave radiation. The effect of the heating on the treated tissue is two-fold. First, hollow structures will be sealed, and permanent occlusion of the structure achieved. Second, the surrounding tissue that is heated will be coagulated, causing cell death and shrinkage.
Conventional methods for administering thermal ablation to hollow anatomical structures, such as the vasculature or various ducts in the body, are typically based on the use of one or more therapeutic catheters that are slidably mounted over a prepositioned guidewire. The disadvantage of this system is that the arrangement sets functional limitations upon the minimum lumen diameter of the anatomical structure that can be treated due to the combined diameter of guidewire and catheter. Hence, for oncology, paediatric/neonatal, neurovascular, cerebrovascular or cardiovascular applications, where the lumen diameters can be very small, such percutaneous or endoscopic thermal ablation techniques can be unsuitable.
Hence there is a need for improved apparatus and methods for managing occlusion of hollow anatomical structures and thermally ablating tissues. In particular, there is a need for methods and apparatus that can be directed to blockage of blood vessels at remote sites within the body that are inaccessible to conventional surgical techniques, such as the brain and the smaller vessels of the heart. There is further need for methods and apparatus for occluding or treating hollow anatomical structures within the body that are not comprised within the vasculature via endoscopic or laparoscopic routes.